In some modern steam power plants of large capacity, high temperature saturated steam is produced in a steam generator and used to drive steam turbines. After passing through a high pressure turbine, the steam is used to drive another turbine at lower steam pressures. Conventionally, the wet steam leaving the high pressure turbine is dried and reheated before being used to drive the lower pressure turbines. This is accomplished in an apparatus which is often separate from the steam generator. The apparatus removes the moisture entrained in the steam leaving the high pressure turbine and also reheats the steam so that it is of a quality suitable for driving the lower pressure turbines.
To be efficient, the apparatus for removing the moisture from and reheating the steam leaving a high pressure turbine must treat a large amount of steam at minimal pressure drop. The apparatus must be able to remove all or most of the moisture entrained in the steam leaving the high pressure turbine and to reheat the steam to a quality which allows efficient operation of the lower pressure turbines.
In the past it has been found difficult to design a moisture separator and reheater apparatus which will treat a large volume of steam flowing at a high velocity and which contains much moisture. The moisture separator and reheater apparatus can become overloaded to the point where it no longer removes all of the moisture from the steam and thereby reduces the overall efficiency of the plant.